ESSENTIAL ORGANS. THE PISTIL. 



211 



fraxineum (fig. 380). In the Tulip-tree (fig. 306), the separate car- 

 pels, c c, are numerous, and arranged in a spiral cycle, upon an elon- 

 gated axis or receptacle. In the Raspberry, the carpels are on a 

 conical receptacle ; in the Strawberry, on a swollen succulent one ; and 

 in the Rose (fig. 270 o o), on a concave one, r r, covered by the tube 

 of the calyx, c t. 



435. When the fruit consists of several rows of carpels on a flat 

 receptacle, the innermost have their margins directed to the centre, 

 while those of the outer rows are arranged on the back of the inner 

 ones ; if the receptacle is convex, the outer carpels are lowest, as in the 

 Strawberry ; if concave, the outer ones are uppermost, as in the Rose. 

 At other tunes the carpels are united, as in the Pear, Arbutus, and 

 Chickweed, so that the pistil becomes syncarpous (avv, together or 

 united). In Dictamnus Fraxinella (fig. 382), five carpels unite to form 

 a compound pistil. In Scilla italica (fig. 259), the three carpels form 

 only one apparently ; but on examination it will be found that the 

 pistil consists of three carpels alternating with the three inner stamens. 

 The union, however, is not always complete ; it may take place by the 

 ovaries alone, while the styles and stigmata remain free, the pistil being 

 then gamogastrous (ya.pos, union, and "/etar^, ovary) ; and in this case, 

 when the ovaries form apparently a single body, this organ receives the 



Fig. 380. Pistil of Zanthoxylon fraxineum, consisting of five distinct carpels, supported on a 

 gynophore, g. Each of the ovaries, o, bears a terminal style dilated at its extremity into a 

 stigma, s. The five stigmata remain for a long time adherent by their sides. 



Fig. 381. 1. Carpels of Butomus umbellatus, consisting of folded leaves arranged in different 

 verticils. 2. Section of the same, showing the alternation of the parts of the flower. Three 

 outer leaves of the perianth, o', alternating with three inner ones, p i, three rows of stamens, e o 

 and e i, and the carpels, c e anil c i. 



Fig. 382. Portion of the pistil of Dictamnus Fraxinella. Two of the five carpels have been 

 removed in order to show how the styles, s, produced on the inner side of the carpels, and at 

 first distinct, approximate and become united into one. o, Ovaries, two of which in front show 

 their dorsal surface, d, and their lateral surface, I. At the base of the gynophore, g, are seen 

 the cicatrices, c, marking the insertion of the calyx, the petals, and the stamens. 



